Chandra D. Holifield Collins

Learn More
Surface roughness is a crucial input for radar backscatter models. Roughness measurements of root meansquared height (hrms) of the same surface can vary depending on the measuring instrument and how the data are processed. This letter addresses the error in hrms associated with instrument bias and instrument deployment issues such as number and length of(More)
The Integral Equation Method (IEM) model and a newly defined delta index were used to estimate near surface soil moisture from C-band radar satellite imagery in a semi-arid rangeland in southern Arizona, USA. Model results were validated against soil moisture measurements made in the field at the time of satellite overpass. The IEM model performed poorly in(More)
[1] The USDA Agricultural Research Service, Southwest Watershed Research Center, Walnut Gulch Experimental Watershed (WGEW), is located in the San Pedro Valley of southeastern Arizona. It is one of the most highly instrumented semiarid experimental watersheds in the world and has one of the largest published collections of spectral imagery with coordinated(More)
The Integral Equation Model (IEM) is the most widely-used, physically based radar backscatter model for sparsely vegetated landscapes. In general, IEM quantifies the magnitude of backscattering as a function of moisture content and surface roughness, which are unknown, and the known radar configurations. Estimating surface roughness or soil moisture by(More)
a r t i c l e i n f o Land surface model parameter estimation can be performed using soil moisture information provided by synthetic aperture radar imagery. The presence of speckle necessitates aggregating backscatter measurements over large (N 100 m × 100 m) land areas in order to derive reliable soil moisture information from imagery, and a model(More)
  • 1